Maximum card issue "The 500th Anniversary of Mazovia's Incorporation into the Kingdom of Poland" 

Catalogue number: 5527 
Issue date: 10-09-2026 

Polish Post issued the commemorative stamp issue “500th Anniversary of the Incorporation of Mazovia into the Kingdom of Poland”, prepared in cooperation with the Marshal's Office of the Mazovian Voivodeship in Warsaw.

The issue commemorates one of the most important events in the history of Mazovia and the process of unifying the Polish lands. In 1526, following the death of the last Mazovian dukes of the Piast dynasty, Stanisław I and Janusz III, Mazovia was incorporated into the Kingdom of Poland. This event ended several centuries of political independence of the Duchy of Mazovia and marked an important stage in the consolidation of the Polish state under the Crown.

The stamp features a historical map of Mazovia, showing the territorial divisions of the duchy before its incorporation into the Kingdom of Poland. The design emphasizes the historical nature of the issue and refers to the cartographic traditions and historical documents of the period. The map recalls the rich history of a region that played a significant role in the development of Poland and whose political center was Warsaw, the future capital of the Polish state.

The sheet consists of 6 postage stamps arranged in a 3 × 2 layout. The artwork is inspired by historical documents, seals and symbols associated with late medieval Mazovia.

The central element is the medium heraldic seal of the Mazovian dukes Stanisław I and Janusz III, displaying the heraldic emblems of the Mazovian branch of the Piast dynasty. Enlarged fragments of the seal appear on both sides of the sheet, creating a monumental backdrop for the stamps.

The design uses warm shades of red, brown, gold and parchment colours, evoking medieval charters, royal acts and official seals.

The sheet tells the story of the end of Mazovia's political independence and its lasting integration into the Crown of the Kingdom of Poland.

The First Day Cover and the commemorative postmark feature a fragment of the heraldic seal of the Mazovian dukes Stanisław I and Janusz III, one of the most recognizable symbols of historic Mazovia.